1 / 13

林維豪 2005. 5.25

CMFB. 林維豪 2005. 5.25. Outline. Introduction of CMFB Some structure of CMFB. Outline. Introduction of CMFB Some structure of CMFB. Why CMFB. When use fully differential, we need Common mode feedback Output : Define the output common mode voltage

selene
Download Presentation

林維豪 2005. 5.25

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CMFB 林維豪 2005. 5.25

  2. Outline • Introduction of CMFB • Some structure of CMFB

  3. Outline • Introduction of CMFB • Some structure of CMFB

  4. Why CMFB • When use fully differential, we need Common mode feedback • Output : Define the output common mode voltage • Input: With DC variation, stable the output common mode voltage • Suppress Acm-dm

  5. The basic structure of CMFB Treated as small signal

  6. Small signal model • CMFB bandwidth should be larger than differential mode

  7. Outline • Introduction of CMFB • Some structure of CMFB

  8. Sense Amplifier • Advantage : Linear sense • Disadvantage : Loading effect • Advantage : Linear sense • Disadvantage : Limit swing

  9. Error Amplifier • Advantage : High Gain • Disadvantage :1.Limit swing 2.Suffer non-linearity and mismatch

  10. Exmple

  11. Voltage control resistor • Advantage : Light loading effect • Disadvantage :1.Limit swing 2.Small gain

  12. Low voltage

  13. Switch capacitor • Advantage : 1.No swing limitation 2. Avoid R loading effect • Disadvantage :1.Longer settling time 2.Increase C output load 3.Need clock

More Related